1. Field of the Invention:
This invention relates to an improvement of a method for forming a metal base composite by molten metal infiltration.
A metal base composite is a material in which a reinforcing material in shape as fiber, flake, or powder, is embedded in a matrix metal, to improve such properties of the matrix metal as strength, rigidity and heat resistance.
2. Description of the Prior Art
Conventionally, metal base composites have been manufactured by molten metal infiltration, diffusion bonding or other methods.
In the infiltration method, molten metal is made to contact and impregnate into a preform of a reinforcing material formed in required shape, density and orientation and then solidified to make a metal base composite. The reinforcing material should be preliminarily heated above a certain temperature, in order to prevent solidification of the molten matrix metal before it has made sufficient impregnation into the preform of the reinforcing material.
The density and the orientation of a reinforcing material affect performance of a composite to be fabricated. The shape of the preform of a reinforcing material is determined according to the shape of a final product of the composite. Therefore in order to obtain a metal base composite with desired performance and shape, the shape, density and orientation of the preform of the reinforcing material should be kept constant through the processes of the contact, impregnation and solidification of molten metal.
The shape, density and orientation of the reinforcing material are conventionally retained by
(1) preliminary forming the reinforcing material in a mat or a felt form, or PA1 (2) constraining and retaining the preform within a casting mold.
However, Method (1) has a disadvantage that the material, density and orientation of the reinforcing material are limited because the reinforcing material is shaped in a mat or a felt form.
Method (2) has a disadvantage that the reinforcing material preliminarily heated may be cooled by contact with a casting mold.